The Veyron is definitely not the fastest real car available in that game
F1 McLaren with 888BHP weighing less than 800Kg is pretty quick... then there are Formula cars which go twice as fast... and to top it off an imaginary F1 car designed by RedBull called the X1 which does Nurburgring in less than 3min30 seconds

but that's just boring;:
the real world <600BHP cars are more fun to drive

but not too fun to drive;
the lesser powered cars are sometimes so much more enjoyable

like the Shelby Cobra vs R8 duel (4th pic first post), Shelby has more BHP, is RWD, but harder to handle, R8 less power, 4WD, but better on the road, end result is a very close race, after 5 laps the difference going over the finish line was less than 0.2 seconds